1. The Field of the Invention
This invention relates to digital computers, and more particularly, to unique apparatus and methods for conserving and managing power allocated to expansion cards and other devices within a computer system.
2. The Relevant Art
In an effort to increase the functionality, flexibility, and utility of today's personal computers, workstations, servers, and the like, expansion buses such as the PCI (Peripheral Component Interconnect) bus have been provided to enable a user to mix and match desired add-on components in a computer system. Expansion buses typically interface with the main bus or local bus connected to a CPU through a bridge or other interface device. Thus, an expansion bus may operate at a different clock speed and may use different data transfer protocols than are used by a CPU and associated components connected to a local bus.
As add-on or expansion components continue to have improved performance, various existing expansion bus technologies may be reaching their limits in terms of data rates, power consumption, expandability, and the like. Moreover, as performance of these components continues to increase, the amount of power these components consume becomes an important issue to proper operation of an expansion bus. Most buses are designed to allocate pre-determined amounts of power to components connected thereto. For example, the PCI bus specification allocates 25 watts to each connected device. Nevertheless, certain components may exceed this rated allotment at times, thereby overloading the bus and associated power supply.
Power supplies are often expensive compared to other components in a computer system. The cost of a power supply may be directly related to its rated wattage. Thus, providing a power supply that is sufficient for a system, with little excess capacity, may contribute to keeping the cost of computers relatively low. Moreover, apparatus and methods used to decrease power consumed by components in a computer may enable a computer to have a lower rated power supply.
Moreover, various expansion cards may use excessive amounts of power, even when used very little. That is, due to leakage currents, high clock speeds, and the like, even when an expansion card is doing very little actual work or processing, power may be unnecessarily wasted. The use of multiple expansion cards may compound this problem, each consuming more power than is necessary. Situations such as these may easily overload rated power supplied by a bus, such as a PCI bus. Moreover, as various computing components continue to decrease in size while they increase in performance, the need for more power may make the devices larger than is necessary due to battery size.
Thus, apparatus and methods are needed to regulate, allocate, and control power provided to devices, such as expansion and add-on cards connected within a computer system. Apparatus and methods are further needed to adjust device parameters such as clock speed, logic wait states, and the like within an expansion or other device to decrease the power required by such devices.